System and method for delivering fluids to a balloon catheter

ABSTRACT

A fluid delivery system includes a first pressurizing device, a second pressurizing device, a reusable fluid path for delivering fluid to multiple patients and a per-patient disposable fluid path adapted to be connected to the reusable fluid path and operable to deliver fluid media to a balloon catheter in a patient. The reusable fluid path includes a first portion in fluid communication with a first source of fluid medium and a second portion in fluid communication with a second source of fluid medium. The first pressurizing device is associated with the first portion of the reusable fluid path and the second pressurizing device is associated with the second portion of the reusable fluid path. A control unit in communication with the first and second pressurizing devices is adapted to actuate the first and second pressurizing devices to deliver one or both of the fluid media to a balloon on the balloon catheter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of pending U.S. patent applicationSer. No. 10/775,235, filed Feb. 11, 2004, which is a DivisionalApplication of pending U.S. patent application Ser. No. 09/749,894,filed Dec. 29, 2000, now U.S. Pat. No. 6,889,074, which is a divisionalof U.S. patent application Ser. No. 09/197,773, filed Nov. 23, 1998, nowU.S. Pat. No. 6,385,483, which is a divisional of U.S. patentapplication Ser. No. 08/309,820, filed Sep. 21, 1994, now U.S. Pat. No.5,840,026, the contents of all of which are incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates generally to the field of medical devices fordelivering contrast media during medical diagnostic and therapeuticimaging procedures and more particularly, this invention relates toimproved contrast media delivery systems and methods of use which allowadjustment of contrast media concentration and injection parameterseither before or during an injection procedure to provide patientspecific dosing of contrast media, thus decreasing the waste and cost ofthese procedures while increasing their efficiency.

DESCRIPTION OF THE RELATED ART

It is well recognized that the appropriate dose for many medications isrelated to the size and weight of the patient being treated. This isreadily apparent in the difference between the recommended doses whichmost medications have for adults and children. The appropriate dose ofcontrast media for a given medical imaging procedure is equallydependent upon the size and weight of the patient being examined as wellas other additional factors.

Although differences in dosing requirements for medical imagingprocedures have been recognized, conventional medical imaging procedurescontinue to use pre-set doses or standard delivery protocols forinjecting contrast media during medical imaging procedures. Using fixedprotocols for delivery simplifies the procedure, however, providing thesame amount of contrast media to patients weighing between 100 and 200pounds, for example, produces very different results in image contrastand quality. If the amount of contrast media used is adequate to obtainsatisfactory imaging for the 200 pound person, then it is likely thatthe 100 pound person will receive more contrast media than necessary forthe procedure to produce a diagnostic image. With high contrast costs,this is a waste of money as well as increased patient risk.

Standard protocols are used primarily to minimize the potential forerrors by hospital personnel and decrease the likelihood of having torepeat the procedure, an occurrence which requires that the patient beexposed to additional radiation and contrast media. Furthermore, inprior art contrast delivery systems, once a bottle of contrast media wasopened for use on a patient it could not be used on another patient dueto contamination considerations. Existing contrast delivery systems donot prevent the source of contrast media used for an injection frombeing contaminated with body fluids of the patient. The containers whichsupplied the contrast media were generally therefore all single usecontainers and, consequently, the entire container of contrast media wasgiven to the patient being studied.

Present protocols include delivery rate in volume per unit time. Usuallythe injection is at a constant flow rate or with one change between twofixed flow rates. However, physically, pressure drives fluid flow. Thus,present fluid delivery systems employ some type of servo to develop thepressure needed to deliver the programmed flow rate, up to some pressurelimit. The pressure needed depends upon the viscosity of the fluid, theresistance of the fluid path, and the flow rate desired. This isconsiderably better than the older injector systems which controlledpressure at a set value, and let the flow rate vary.

There are significant drawbacks to fluid delivery systems which areunable to adjust the concentration of contrast media and other injectionparameters during an injection procedure. Many patients may receive morecontrast media than is necessary to produce an image of diagnosticquality, while others may receive an amount of contrast mediainsufficient for producing a satisfactory image. Existing proceduresalso frequently result in waste of contrast media as well as the needfor repeating the procedure because an image of diagnostic quality couldnot be produced.

Some of the shortcomings of existing procedures have been addressed andresolved as described in application Ser. No. 08/144,162, titled “TotalSystem for Contrast Delivery,” filed Oct. 28, 1993, now abandoned, andincorporated herein by reference. This application discloses a contrastmedia delivery system which provides a source of contrast media that issufficiently isolated from a patient undergoing an imaging procedurethat the source of contrast media may be used on additional patientswithout concern for contamination. Additionally, this system is capableof adjusting contrast media concentration and other injection parametersduring an injection procedure.

The system incorporates a source of contrast media and, if desired, adiluent. Each is sufficiently isolated from the patient to preventcontamination. The contrast media preferably has a concentration whichis the highest that would be used in an injection procedure so that theoperator may combine the contrast media with a diluent and selectvirtually any concentration of contrast media desired for any givenprocedure. The concentration of the contrast media injected into apatient may be varied during the injection procedure by varying theratio of diluent to contrast media. Each patient therefore receives onlythe amount of contrast media necessary to provide a proper diagnosticimage.

It is recognized that this system will be much more versatile and usefulif the operator is able to select and adjust contrast mediaconcentration and other injection parameters based on patientinformation or feedback received during the injection imagingprocedures. Additionally, this system would be more efficient if it werecapable of automatically choosing the appropriate concentration andinjection rate for a given patient. Even more utility and efficiencywould be realized from a system that is capable of automaticallyadjusting concentration and other injection parameters during aninjection procedure based on feedback related to the resultant imagequality.

Accordingly, it is an object of this invention to provide an improvedcontrast media delivery system which is capable of automatically varyingthe injection rate and concentration of contrast media given to apatient during an imaging procedure, based on information receivedeither before or during the injection procedure.

It is another object of the present invention to provide an improvedcontrast media delivery system which obtains and utilizes feedbackinformation during the imaging procedure to automatically adjust theflow rate, volume and/or concentration of the contrast media into thepatient if needed.

It is a further object of this invention to provide a system which iscapable of selecting the appropriate injection flow rate andconcentration for a given patient based on patient information enteredinto the system.

Numerous other objects and advantages of the present invention willbecome apparent from the following summary, drawings, and detaileddescription of the invention and its preferred embodiment.

SUMMARY OF THE INVENTION

The invention includes apparatus and methods for medical contrastimaging and comprises embodiments which provide patient specific dosingof contrast media in a variety of medical imaging procedures, as opposedto fixed protocols. In this invention, the protocol variables aredetermined by the system and are dependent upon patient specificinformation supplied by the operator, and/or information measured by thecontrast delivery system either prior to, or during the injectionprocedure. These apparatus and procedures disclosed herein apply to allof the systems disclosed and described in the application titled “TotalSystem for Contrast Delivery”, Ser. No. 08/144,462, now abandoned.Further systems are described in which the system receives input from anoperator to provide the appropriate adjustment of system parameters.

In a principal embodiment, information specific to any given patient isentered into the system and the appropriate concentration and injectionparameters are computed before initiating the imaging fluid injectionprocedure. The system is then ready for injection of a patient. It isimportant to note that the system is not limited to choosing aparticular concentration of contrast media or injection rate for theentire procedure, or even a moderate number of phases with constantvelocity as present injectors can now do, but rather is capable ofselecting an injection profile which may include a continuously varyinginjection rate and/or concentration of contrast media. The particularinjection profile selected by the system is designed to provide the bestimage quality for the particular patient based on a variety of factorssuch as patient weight and circulation system variables.

In a refined version of the system, feedback from at least one sensor isemployed by the control system to modify the concentration of thecontrast media, injection rate, and/or total volume during the injectionprocedure. Various types of sensors are disclosed for use with thissystem, in particular, various electromagnetic sensors or videomonitoring devices provide feedback for the system or operator to use.In angiography, where the contrast is injected into the region ofinterest, the sensor needs to make a measurement in that region ofinterest. In CT and MR it is sufficient for the sensor to measure aremote area of the body, although measuring within the region ofinterest (ROI) could be advantageous in some applications. The sensorprovides an indication of the actual amount of contrast media in thepatient. This is used to calculate the appropriate injection rate orconcentration of contrast media to provide a diagnostic image withminimum risk and cost.

In critical locations such as coronary arteries, it will take a whilefor doctors to have confidence in automatically controlled fluiddelivery system, thus, rather than automatically altering injectionparameters based on feedback signals received from automatic sensors,the concentration, or other injection parameters may be manuallyadjusted based on images seen by the doctor or operator.

A final version of the invention is disclosed which works to furtherimprove doctors confidence by providing tactile feedback to a doctor oroperator in addition to visual or other sensed feedback on the amount ofcontrast media in a patient. This provides the operator with additionalinformation to use in determining injection rate, concentration andpressure for the injection procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram illustrating the prior art procedure forimplementing a standard protocol.

FIG. 2 is a flow diagram for a system of the present invention in whichinjection parameters are calculated based on patient specificinformation.

FIG. 3 a illustrates an embodiment of the present invention whichemploys the improved procedure for calculating injection parameters ofthe present invention.

FIG. 3 b illustrates an embodiment of the present invention whichemploys the improved procedure for calculating the filling of a syringeused with an injector.

FIG. 4 is a flow diagram outlining an injection procedure whichincorporates a sensor for sensing contrast concentration in a patientduring a test injection.

FIG. 5 is a flow diagram outlining an injection procedure whichincorporates a sensor for sensing contrast concentration in a patientfor modifying the injection parameters throughout the injection.

FIG. 6 illustrates an example of a sensor for use with the presentinvention.

FIG. 7 illustrates the present invention wherein the system is able toautomatically adjust fluid flow rate based on the resulting image.

FIG. 8 illustrates an embodiment of a tactile feedback pressuremeasurement device which allows the system operator to adjust injectionparameters based on tactile feedback.

FIG. 9 illustrates an embodiment of the present invention whichincorporates a Tactile Feedback Control (TFC) unit which allows thesystem operator to adjust injection parameters based on this sensor aswell as the resulting image. The TFC is in fluid communication with thefluid being injected.

FIG. 10 a illustrates an embodiment of the present invention whichincorporates a Tactile Feedback Control (TFC) unit which allows thesystem operator to adjust injection parameters based on this sensor aswell as the resulting image. The TFC is not in fluid communication withthe fluid being injected.

FIG. 10 b illustrates an embodiment of the TFC in greater detail.

FIGS. 11 a-d illustrate various relationships between TFC inputs andcontrast delivery system actions which an operator could select with thesystem.

FIG. 12 illustrates disposable manifolds operated by electronicsolenoids or motors which are designed for use with the presentinvention during cardiology.

FIG. 13 illustrates a manifold for use with the present invention duringcardiology procedures.

FIG. 14 illustrates a system by which the manifold illustrated in FIG.13 is voice-activated.

DETAILED DESCRIPTION OF THE INVENTION AND ITS PREFERRED EMBODIMENT

FIG. 1 is a flow diagram showing a conventional medical imagingprocedure for implementation of a standard protocol. This diagram isindicated generally by the numeral 10. The imaging procedure standardprotocol is selected at first operative step 11, and a decision is madeat step 12 as to whether the patient's weight is within a broad rangeconsidered to be appropriate for the particular concentration ofcontrast media and set of injection parameters for the selectedprotocol. If the patient's weight is within the broad range of weightsacceptable for the particular contrast media and set of injectionparameters, the standard protocol is determined to be appropriate atstep 14. The patient is injected and the image is acquired at step 18.Alternatively, if the weight of the patient is not within the givenrange, an alternate contrast media concentration and set of injectionparameters are chosen at step 16. Once the alternate concentration orset of injection parameters are chosen at step 16, the patient is theninjected and the image is acquired at step 18. The operator then reviewsthe image at step 20. If the image is satisfactory, the procedure issuccessfully completed and the system is prepared for the next imagingprocedure with this patient or another patient at step 22.

If the image is not satisfactory, the procedure must be repeated asnoted at step 24. A decision is then made as to whether there is aspecific problem with the system or selected protocol at step 26. Ifthere is a problem with the protocol, the selected protocol is revisedat step 28. Alternatively, if the initially selected protocol isappropriate, step 14 is repeated and the patient is injected at step 18.As noted, this type of system and its lack of versatility hassignificant disadvantages compared with the system of the presentinvention.

The present invention takes advantage of the increased versatility ofthe advances set forth in the co-pending application previously notedand further advances the art by adding automatic functions and increasedversatility.

A flow-diagram illustrating an improved contrast media delivery of thepresent invention is shown generally by the numeral 30 in FIG. 2. Inthis system the operator initially inputs information relating to thepatient such as size and weight in addition to other factors related tothe particular imaging procedure being performed at first operative step32. This information could be stored in a hospital computer and simplydownloaded to the imaging system. The Electronic Control System (ECS) ofthe contrast media delivery system then determines the appropriateconcentration of the contrast media and other injection parameters suchas flow rates, volume, time delay, etc. at step 34. The computedconcentration of contrast media and injection parameters are thendisplayed at step 36.

In this and other embodiments, the step of displaying parameters foruser review is optional. As this capability is first introduced,operators will want to retain control. As they become familiar with theequipment and gain confidence with it, it will be possible tomanufacture and market systems which no longer display injectionparameters for operator review. In the preferred embodiment, however,the system operator then reviews the calculated parameters at step 38and decides whether to manually modify the parameters at step 40 orproceed with the injection of the patient at step 42. The injectionbegins in step 42, the image is acquired, and the system operator orphysician reviews the resulting image at step 44. If the image issatisfactory for diagnosis, the image is stored and the procedure iscomplete. The system may be prepared for the next imaging procedure atstep 46. Prior to preparing the system for the next imaging procedure,the operator may choose to perform optional step 47 in which theoperator may input information to modify the algorithm which determinesthe injection parameters so that before the system stores the parametersthey are set to levels which would have provided an image which is morepersonally satisfactory. The system software keeps track of the variousinjection parameters a doctor or operator selects for patients of aparticular size and for a given procedure. These factors are analyzedfor preferred tendencies of the doctor or operator so that the system isable to select injection parameters based on the operators personalpreferences. By performing this optional step, the system will be ableto automatically select operating parameters which provide a moresatisfactory image for an individual. If the operator chooses to performoptional step 47, the system is prepared for the next imaging procedureupon completion of this step.

Alternatively, if the image is not satisfactory, the image parametersare extracted at step 48 and the ECS is updated at step 49. The ECS thenrecalculates new parameters and repeats step 34. The remainder of theprocedure is also repeated. It is anticipated that this will happen veryseldom once the algorithm is adapted to the doctor's preference.

FIG. 3 a illustrates an embodiment of the improved contrast mediadelivery system of the present invention generally at 50. The userinterface of the ECS is indicated at 52 with direct connection to theECS 54. There is an additional electronic interface 56. The electronicinterface 56 may be connected to other systems which are not shown, suchas imaging equipment and the hospital information system. If thisinterface is connected to the hospital information system, it could relyon this system to receive patient specific information necessary forperforming the procedure such as size, weight, etc. An operator wouldtherefore only be required to input a patient number and the appropriateinformation would be downloaded from the hospital information system.

The electronic interface 56 is also connected to the imaging equipment57. The ECS is capable of sending and receiving information so that, forexample, the operator only needs to program the CT scanner with thenumber of slices and section of the body being imaged. This would betransmitted to the contrast delivery system to be used in determiningflow rates and delays, etc. Additionally, information relating to imagequality or sensed concentration of contrast media is received to allowfor automatic adjustment of the system.

An information scanner 58 is also shown with direct connection to theECS 54. The information scanner 58 scans information encoded andattached to fluid storage tanks for the contrast container 60 anddiluent container 62. The information encoded and read by the scanner 58includes information such as tank volume, type and concentration offluid etc. This information is then employed by the ECS in controllingand calculating the implementation of the imaging procedure.Alternatively, this information is downloaded from memory located on afluid delivery module as noted in the application titled Closed LoopInformation Path for Medical Fluid Delivery Systems, application Ser.No. 08/273,665, filed Jul. 12, 1994, now abandoned.

Contrast and diluent tank volume, type and concentration of fluid isstored in the system memory and is updated after using the system. Thesystem is therefore able to automatically warn the operator when thesystem is running low on contrast or diluent. Additionally, the systemis able to warn the operator if the wrong contrast media was connectedfor a particular procedure.

The ECS 54 is also connected to respective contrast and diluent heaters64, 65. The ECS 54 controls the heaters 64, 65 through this connectionand receives feedback so that the system may make appropriate adjustmentof the heaters to provide the desired temperature of contrast media.Metering pumps 68, 69 are connected to the ECS 54 which also controlsfluid flow of contrast and diluent through the pumps.

The output of each of the metering pumps 68, 69 is connected to thehelical vane static mixer 71 which ensures that the desiredconcentration of contrast media is produced by the system. A backflowvalve 73 in the fluid flow path to the patient prevents the contrastmedia from returning to the sources of contrast and diluent 60, 62 andcausing contamination. A fluid assurance sensor 75 is also directlyconnected to the ECS 54. The final element in the fluid path which isconnected to the ECS 54 is the pressurizing pump 76. The pressurizingpump 76 provides the desired injection rate of contrast media for theparticular procedure. A per patient connector 77 is followed by asterile filter 78 which is also connected in line to preventcontamination of the sources of contrast media and diluent by preventingbody fluids of the patient from flowing back into the sources ofcontrast and diluent. The fluid path then flows through connector tube80 and a medical stopcock 82.

A hand held syringe 84 is also connected to a port of the stopcock 82 toallow the doctor to perform what are considered test or scoutinjections. For example, the doctor may get a small amount of fluid at aconcentration, and then do hand powered injections during hismanipulations to get a catheter into the proper vessel. In a preferredembodiment, a contrast media sensor (not shown) is added to the systemto provide additional feedback during an injection procedure in order toprovide for better monitoring of concentration as it is adjusted by thesystem.

FIG. 3 b illustrates a second embodiment of the improved contrast mediadelivery system of the present invention generally at 50. Most of thesystem components and their function are identical to those of FIG. 3 a,but instead of the per patient connector 77, sterile filter 78, tubing80, connector 82 and hand syringe 84, 3 b has a syringe 79 which isfilled with fluid. This syringe is then placed in an injector fordelivery of the fluid to the patient. Prevention of contamination isaccomplished by having the syringe allowed to be filled only once. Thelabel printer prints the patient specific injection information, andthis label is then read by the ECS of the injector. The injector ECS 35can utilize any of the improved patient specific processes of thisinvention, such as sensors or tactile feedback controllers, neither ofwhich are shown.

Alternatively, the injector ECS 35 could communicate with the fillingstation ECS 54 so that the injector is programmed by the fillingstation. A third alternative involves having the filling station userinterface 52 display the injector parameters and then the operatorenters these parameters into injector ECS 35 via the injector userinterface. An advantage of this most manual system is that it can workwith present injector equipment, enabling the customer to achievepatient specific dosing while utilizing equipment which he has alreadypurchased.

One embodiment, not shown, that uses even less hardware andsophistication consists of only a user interface and an electroniccontrol system. The operator enters the patient specific data, and thevolume, concentration and injection parameters are displayed for theoperator. Then the operator manually fills the syringe using a manualmethod, such as that supplied by NAMIC, of Glens Falls, N.Y., preservingany unused contrast for the next patient. The injector is thenautomatically or manually programmed according to the patient specificparameters computed, and is ready to inject.

It will be appreciated that various devices could be employed tofunction as the ECS 54. ECS 54 at the very least must incorporate amicroprocessor and memory along with control outputs for the variousdevices. It is understood that software controls the system. Thesoftware relies on a variety of factors for calculating the appropriatecontrast media concentration and injection parameters for a particularpatient.

The appropriate weight given to each of the factors in the software forcalculating these parameters cannot now be disclosed because of thevaried relationship between these factors and the numerous imagingsystems and sensors which may use this invention. It is contemplatedthat experimentation with various weight factors applied to thevariables will provide the best results with any given system. This iswhy embodiments are described with varying degrees of operator control,operator verification and automatic operation.

The following table provides an outline of the factors which the systemmay consider in evaluating the appropriate concentration of contrastmedia and injection rate for a particular patient as well as the generaleffect an increase in these factors would have on calculation of theinjection parameters. Some factors such as weight have a continuouseffect. A slightly heavier patient gets a little more contrast. Others,such as hydration or kidney function have no effect until some thresholdis crossed. TABLE I INPUT PARAMETER EFFECTED PARAMETER EFFECT FOR INTRAVENOUS Patient Weight Total volume Increases (mg of Iodine) Flow rate toget Increases mgl/kg/sec Concentration (optional) Increases PatientHydration Concentration Increases Kidney Function Use minimum total mglif poor or questionable Cardiac Status With poor status, use minimumtotal fluid volume to minimize fluid loading Circulation Transit Uselonger delay time Time until start of scanner if circulation time ispoor Change from single phase to multi-phase or continuously varyingLength of Scanning Flow rate Decreases to lengthen image contrast timeConnector tube Provides limit to prevent diameter or catheter overpressure size Patient vein status If weak, use lower concentration,lower FOR INTRA ARTERIAL Vessel Diameter Flow rate Increases Volume ofInjection Increases Concentration Increases Catheter DiameterConcentration Increases Procedure/body Duration of injection Varieslocation Patient Weight Limit on total iodine Increases dose

Given the variety of factors to be considered, fuzzy logic or neuralnetworks may be appropriate for implementation of the program, however,a conventional computer program also provides satisfactory results.

FIG. 4 illustrates a flow-chart of the injection procedure of thepresent invention with sensor measurement. In this procedure, a testinjection is made and a contrast media sensor is used to providefeedback on the actual concentration of contrast media within thepatient. Initially, the operator enters the type of imaging procedure tobe performed and patient information at first operative step 90. It isimportant to note the system will already be aware of the type andconcentration of the fluid available in the system tanks because theinformation scanner would have input this information when the tankswere installed. In the next step 92, the ECS computes the appropriateconcentration of contrast media and the injection parameters such asflow rates, volume, and time delay etc. The resultant concentration andinjection parameters are then displayed at step 94. The operator thenreviews the parameters and decides whether to manually modify theprocedure at step 96.

If the operator is satisfied with the injection parameters, a testinjection of the patient is performed in step 98. Alternatively, theoperator may modify the procedure in step 100 and then perform a testinjection of the patient at step 98. A sensor measurement of theconcentration of contrast media within the patient's body is thenperformed at step 102 and a decision is made at step 104 as to whetherthe results of the sample injection are sufficiently close to thedesired value. If the results of the test injection are notsatisfactory, the system returns to step 100 to modify the injectionparameters, either manually or automatically and then repeats the testinjection at step 98.

When the results of the test injection are satisfactory, the finalinjection parameters are selected at step 106 which may involve havingthe operator fine tune the procedure by making minor adjustments andupdating specific parameters to provide more desirable results. If moresignificant changes are needed, the test injection should be repeated asnoted. The imaging injection procedure begins at step 108. Uponcompletion of the injection procedure step 108, the operator reviews theimage at step 110 and determines whether the procedure produced asatisfactory diagnostic image. If the image is satisfactory, theprocedure is complete and the system may be prepared for the nextimaging procedure at step 112. Step 113 is an optional step which may beperformed before preparing the system for the next imaging procedure ifthe operator wishes to update the algorithm which determines theinjection parameters that are used to customize injection procedure to adoctor's preference.

Alternatively, if the image is unsatisfactory, the image parameters areextracted at step 114 and the ECS injection parameters are updated atstep 115. The procedure is repeated beginning with recalculation of theinjection parameters step 92. It is anticipated that this will happenvery seldom once the algorithm has been adapted to the imaging equipmentand the doctor's preferences as previously noted.

FIG. 5 illustrates an alternate procedure for performing an imagingprocedure with the improved contrast delivery system of the presentinvention. In this procedure, a sensor measurement is used throughoutthe injection procedure to provide an indication of the actualconcentration of contrast media within the patient. Initially,information relating to the particular imaging procedure to be performedand patient are input to the system at step first operative step 116.The ECS computes concentration, and other injection parameters such asflow rates, volume, time delay, etc. at step 117. The calculatedconcentration of contrast media and other injection parameters are thendisplayed at step 119 and the operator reviews the calculated resultsand determines whether they are satisfactory at step 120. If the resultsappear to be within the desired range, injection of the contrast mediabegins in step 122.

Alternatively, the operator may modify the injection parameters at step123 before initiating the injection at step 122. A sensor measurement ismade at step 125 and a decision is made as to whether the results aresatisfactory at step 126. If they are not satisfactory, the injectionparameters are modified at step 127 and the sensor measurement iscontinued at step 125. The sensor measurement is made and the injectionparameters are adjusted throughout the injection process based on thesensor measurements. The adjustments continue until the procedure iscomplete as indicated at step 128. If the sensor measurement indicates aserious problem, the system may automatically stop the injectionprocedure depending on the severity of the problem. Upon completion, theoperator then reviews the image at step 130 and decides whether theresults are satisfactory.

If satisfactory results are achieved, the system is prepared for thenext imaging procedure as indicated at step 132. Step 133 is an optionalstep which may be performed before preparing the system for the nextimaging procedure if the operator wishes to update the algorithm whichdetermines the injection parameters to customize the injection procedureto a doctor's preference.

Alternatively, if the results are not satisfactory, the image parametersare extracted at step 134 and the ECS injection parameters are updatedat step 136. The ECS then recalculates the concentration of contrastmedia and injection parameters at step 117 and the operator repeatsremaining steps in the procedure. Again, this will be a seldomoccurrence once the doctor's preferences have been included. In thisembodiment and all others, the repeat procedure may need to be postponedif the patient is near the maximum daily contrast dose.

Having the sensor provide to the ECS, a measure of contrast in the bodyduring an injection and having the ECS be able to continuously adjustfluid concentration, flow rate, and/or timing of the signals to startthe imaging equipment provides an ability to optimally adapt the dosingto patient specific parameters which may be unknown or inaccuratelyestimated before the start of the injection. For example, in a CTinjection, contrast may arrive at a site more quickly in some patientsthan others.

Systems are available which allow the operator to adjust the timing ofthe beginning of CT scans, however, these systems, unlike the systems ofthe present invention, are unable to adjust the flow rate,concentration, and/or stop the injection sooner than originally planned,thus limiting the amount of contrast injected into the patient, savingmoney and reducing patient risk.

FIG. 6 illustrates an example of a sensor which can be used with theimproved contrast media injection system of the present invention. Thesensor is shown generally at 140. It is contemplated that a variety ofsensors may be used for evaluating the concentration of contrast mediawithin a patient at particular time. These sensors use variouswavelengths of electromagnetic radiation to determine the presence ofcontrast media. The particular sensor disclosed in FIG. 6 is designedfor sensing contrast media used during procedures which use x-rays tocreate the desired image. Therefore this sensor employs a source ofx-rays and a receiver for determining the amount of x-ray radiationwhich passes through the tissue of a patient. It is understood that useof other sensors for x-ray or different types of contrast media could beused in a similar manner.

The sensor includes a silicon diode radiation detector 142 and source ofradioactive material 144. A moveable shield 146 is capable ofalternately shielding and exposing the radioactive material 144 to theradiation detector 142. Electronic actuator 148 moves the shield 146upon command from the ECS. The sensor includes control and power cables150 connected to the ECS not shown. It has been found that a smallradioactive source works best. One example of a commercially availableproduct which can be used to generate an output which varies dependingupon the level of x-rays passing through body tissue is the Lixi scopemanufactured by Lixi, Inc. of Downers Grove, Ill. 60515. This productuses a similar design for portable imaging of small body parts such asthe hand or ankle. Although this product is designed for producingimages, it is also capable of being adapted to provide signals which areproportional to the level of contrast media in a patient. When used withthe system of the present invention, the source and detector are placedon opposite sides of a thin tissue region such as the ear lobe, fingertip, or fleshy part of the hand between the thumb and index finger. Itis known that the attenuation of the tissue will change as theconcentration of x-ray contrast builds up in the blood and thensurrounding tissue. It should be noted that the radioactive sourceshould be shielded when not in use.

Another type of sensor which could be used with the system is one whichemploys visible or infrared (IR) light, preferably of two differentwavelengths. This is similar to the technique currently employed inpulse oximeters. It is known that iodinated contrast interferes with thesignals used to make oxygen measurements with pulse oximeters and thatthese systems are capable of measuring the level of iodinated contrast.Most x-ray contrasts contain a benzene ring with three iodine atomsattached at positions 1, 3 and 5. Various organic molecules are attachedat positions 2, 4 and 6. The infrared spectrum for iodine atoms bondedto a benzene ring is unlike those for naturally occurring compounds.Dual or multiple wavelengths help to minimize interference or preventpositioning differences from giving incorrect readings. Sensors withother visible, IR or different electromagnetic wavelengths would be usedfor MRI or ultrasound contrast materials.

Another sensor which could be used with the improved injection system ofthe present invention is a pressure sensor inserted into a vessel. Atiny pressure sensor on an IC, such as those made by SenSim, Inc.,Sunnyvale, Calif., are capable of providing this type of feedback. Adual lumen catheter and a conventional blood pressure monitor could bealso used. During the injection procedure, the flow rate of the injectorwould be adjusted based upon the sensed intra-luminal pressure. Forintravenous injections, the pressure within the vein could be used tolimit or appropriately adjust flow rate or concentration to preventvessel damage or extravasation. For intra-arterial injections,appropriate adjustment would minimize backflow by timing variations inflow rate to match internal variations due to pressure waves created bythe heart. When backflow occurs, some of the injected contrast movesupstream in the vessel and may go to unintended side vessels. This isnot usually dangerous, but does represent a waste of contrast. Measuringthe pressure at one or more places in the artery or vein duringinjection provides the information which is necessary to safely injectthe optimum amount of contrast.

Regardless of the type of sensor used by the system, it is contemplatedthat the sensor will send a feedback signal to the ECS such as a voltageproportional to the concentration of contrast media present in apatient. The system could then either provide this information to thesystem operator for manual adjustment of the injection parameters, oralternatively, the system could use these signals to automaticallyadjust the concentration of the contrast media or the flow rate toprovide a more desirable image. For intra-arterial, the delay betweenchange in injection parameter and effect is small enough so that theoperator may be part of the feedback loop. For intravenous injections,the delay is longer and variable, so having the ECS measure andautomatically account for the delay is preferable.

FIG. 7 illustrates another embodiment of the present invention. In thisembodiment, the system is capable of automatically adjusting theinjection parameters to alter the image produced by the system basedupon feedback from the actual image. This embodiment includes an imageprocessor 160 which analyzes a bitmap of the video image produced by thecontrast delivery system in conjunction with the imaging equipment 57.The operator 162 selects one area of interest on the image via themonitor 163, for example, by moving a box or pointer over the area via auser interface such as a mouse and then selecting the position byclicking the mouse. The user selects a desired area of interest such asa blood vessel being examined. The image processor 160 then calculatesthe average intensity of the pixels in the designated area. It isunderstood that pixel intensity would be proportional to the amount ofcontrast media in the patient's body due to the effect on theelectromagnetic wave or ultrasonic energy wave being used for theimaging procedure. Depending upon the resultant average pixel intensity,the system then makes appropriate adjustments in contrast concentrationand injection rate.

The use of a video image for providing feedback to make adjustments tothe injection parameters requires real time or approximately real timedisplay of the ROI. All x-ray fluoroscopic systems provide real-timevideo. One such system that is capable of providing such images in CT isa system called Smart Prep manufactured by General Electric ofMilwaukee, Wis. Once the injection is started with this system, a scanis repeated periodically after a small delay. A delay of approximatelyeight seconds is of short enough duration to provide satisfactoryresults. The concentration of the contrast in the ROI's is measured oneach scan and plotted for the operator. In the General Electric system,this plot is used to help the operator decide when to begin scanning theorgan. In the invention described herein, a mechanism similar to GE'smay also be used as the sensor input to the ECS to automatically controlthe flow rate or concentrations.

Another way in which the system of the present invention can use theresulting image for adjusting the injection parameters is for theoperator to select two areas of interest on the image. The systemproduces a relative pixel intensity measurement by calculating thedifference in pixel intensity between the two different areas. Theoperator selects one area located in the background and second arealocated within part of the patient being examined such as a blood vesselof interest. The image processor calculates the appropriateconcentration of contrast media based upon the resulting measurement.

A further embodiment of the present invention is disclosed in FIG. 8.The injection system is shown generally at 170. The ECS 54 is connectedto the contrast delivery system 172 and an embodiment of a TactileFeedback Control (TFC) unit 173. An additional connection is madebetween the ECS and the user display 176. The TFC 173 comprises adisposable syringe 174 which is located within a durable/reusable cradle178. The cradle 178 is electrically connected to the ECS 54 and isphysically connected to a sliding potentiometer 180 which is driven byplunger 181.

The doctor holds the cradle and syringe during the injection procedureand as the doctor depresses the sliding potentiometer/syringe pistonassembly, the plunger is moved forward, displacing fluid toward thepatient and creating a pressure in the syringe. The slidingpotentiometer 180 tracks the position of the syringe plunger.Alternatively, optical encoders could be used to prevent contactskipping thus increasing the system reliability.

The ECS controls the Contrast Delivery System (CDS) to inject an amountof fluid into the patient based on the change in position of theplunger. The disposable syringe 174 is in fluid communication with amulti-port stopcock 182. As the fluid is injected, the pressure thedoctor feels in his hand is proportional to the actual pressure producedby the contrast delivery system. The force required to move the pistonprovides the operator with tactile feedback on the pressure in thesystem. The doctor is able to use this feedback to ensure the safety ofthe injection procedure. Separate from this mechanism, the ECS mayemploy other pressure measurement mechanisms such as the contrastdelivery system motor drive current.

The primary benefit over a totally manual injection is that the doctoris not required to develop the pressure and flow rate. He only developsthe pressure and pushes some of the fluid. The required manual poweroutput (pressure*flow rate) is decreased.

The ECS also incorporates preprogrammed flow rate and pressure limitswhich prevent the pressure of the injection from exceeding safe limits.Additionally, the user display 176 incorporates warning lights whichindicate when certain pressure levels have been exceeded as well as anindication of the actual pressure.

The ECS of the preferred embodiment of the present invention also storesthe injection parameters or flow rate profiles used by individualdoctors or other system operators so that the system is able tocustomize injection procedures to match the particular injection profilepreferred by the individual. It has been recognized that doctors havevarying preferences in the images used for diagnosing patients duringmedical imaging procedures. Varying degrees of contrast mediaconcentration and injection rates alter the contrast in the resultantimage. The system would be able to use information on a doctor'spreference to customize procedures primarily based on the type ofprocedure and the weight of the patient. These and other injectionstatistics would be stored and after a sufficient sample size wasavailable in system memory for the particular doctor or system operator,the system would make minor adjustments to the weight given to variablesin the injection parameter calculation algorithm used by the ECS. Thiswould enable the system to operate in the more automatic modesillustrated in FIG. 2, 4, or 5.

FIG. 9 illustrates the embodiment of the present invention disclosed inFIG. 8, wherein the operator 162 is able to adjust flow rate via theTactile Feedback Control unit (TFC) 174. The operator is able to feelthe actual pressure used during the injection procedure and is able toadjust flow rate based on the resultant image displayed on the videomonitor 163. The system incorporates pressure limitations to preventpatient injury. This system is similar to that shown in FIG. 7, exceptthat the operator views the region of interest, and pushes on the TFC inproportion to the amount of contrast media desired to be injected basedon the resulting image. In addition to the feedback via the video image,the doctor receives pressure feedback via the hand held unit. Doctor arefamiliar with this type of feedback because it is similar to thesituation encountered when a powered fluid delivery system is not used.This increases their confidence when using the system in critical areassuch as coronary vessels. As the operators gain confidence in the safetyand reliability of the system, it will be possible for the systemoperation to be more automatic as shown in FIG. 2, 4, 5, or 7.

FIG. 10 a illustrates use of another embodiment of the present inventionwherein the ECS uses signals generated in the TFC 190 to determine aproportionate amount of fluid to be injected into the patient. In thisembodiment, displacement is proportional to the actual amount of fluiddelivered and the TFC is not in fluid communication with the fluid beingdelivered.

FIG. 10 b shows more details of the TFC unit disclosed in FIG. 10 awhich would eliminate the fluid path connection between the TFC and theactual fluid being injected. It consists of a plunger 200 with athreaded section 201. The base consists of an outside case 205, apressure sensor 207 attached to the case, and a motor 209, the base ofwhich is attached through the pressure sensor 207 to the base of thecase 205. The shaft of the motor is connected to a threaded rod 210. Theplunger 200 freely slides back and forth with respect to the base. Theplunger 200 cannot rotate with respect to the base. On the end of theplunger nearest the base is a threaded section 201. As the threaded rod210 rotates, the plunger 200 is moved in or out, depending upon thedirection of rotation. If desired, a linear potentiometer may beconnected to the plunger to provide a resistance proportional to theposition of the plunger in the base for measurement by the ECS.

To the doctor, the TFC functions as a syringe. When the doctor pushes onthe plunger 200, he generates a force which is sensed by the forcesensor 207. The output of this sensor is proportional to the forceapplied by the doctor. Various types of force sensors may be used suchas, for example, a piezoelectric film or a stiff spring with a lineardisplacement potentiometer. The ECS receives the pressure signal, andgenerates a proportional pressure in the contrast delivery system (CDS).As the fluid is delivered by the CDS, the ECS energizes the motor 209which rotates the threaded cylinder 210. Thus the plunger moves towardthe base as the fluid is being delivered to the patient, and the doctoris sensing a resistance force which is proportional to the pressurerequired to deliver the fluid.

The TFC of FIG. 10 b provides several benefits. It is completelyreusable, because it may be either sterilized or simply covered by abag. The fluid path is simplified, and therefore less expensive, easierto install, fill and assure the removal of air. The TFC can be muchfarther from the patient thereby also allowing the doctor or operator tobe farther from the radiation field and receive less X-ray radiation.Both the ratios between the applied force and pressure in the CDS andbetween flow rate and displacement rate can be varied electronically,whereas in the previously described TFC, the force was set by thediameter of the disposable syringe.

In either of the TFC embodiments shown in FIGS. 8 and 10 b, it ispossible to operate in several modes. In the preferred mode, thedisplacement of the TFC is proportional to the volume of fluid beinginjected, and the rate of fluid injection is proportional to the rate atwhich the plunger of the TFC is displaced. A second mode is describedwith a control system which is similar to that found in a variable speeddrill. In this system, the flow rate of the injection is proportional tothe displacement of the TFC. This mode is not the primary one but may bepreferred by some operators.

The simplest algorithm assumes a linear relationship between the TFCdisplacement and the volume injected or the flow rate being injected.Other relationships are possible. Some examples are given in FIGS. 11a-11 d. In the TFC of FIG. 8, the syringe is actually connected to thefluid line therefore the pressure in the TFC is the same as that at theinjection, and the force felt by the operator is controlled by thediameter of the syringe. In the electronically actuated TFC therelationship between input at the TFC and output from the CDS can followany of the relationships of FIG. 11 or many others as well. Therelationship may be different for different operators. A strong man islikely to prefer a different relationship than a smaller woman. In apreferred embodiment, the system would be configured according toindividual preferences and the operator could simply enter their nameand password to set the desired preferences.

The example in FIG. 1 d describes a relationship that might be used toinflate a balloon for angioplasty. The pressure in the CDS would beincreased in steps as the pressure in the TFC is increased.

Another capability of this embodiment is to synchronize the CDS with anelectrocardiogram signal. Present injectors can be programmed to injecta specific volume at specific flow rate and position relative to amarker on an electrocardiogram such as, for example, the R wave. Thesesystems are preferred by some, but do not have the confidence of others.It is not possible for an operator to manually synchronize with theelectrocardiogram signal, so they inject by hand at a constant rate.This practice results in a waste of contrast media because the fluidflows into vessels which are not being studied. A benefit of the TFC isthat the operator now has the instantaneous control of the injectionwith feedback on pressure and flow rate. The CDS is able to synchronizewith the electrocardiogram thus minimizing the use of contrast mediathus saving cost and dose to the patient.

The selected exemplary embodiments of the TFC units set forth abovedescribe two design choices for the TFC. It is contemplated that varioussubstitutions and modifications could be made to accomplish the resultsof the selected designs. The claims are in no way limited to thesepreferred embodiments.

FIG. 12 illustrates an enhanced version of the system which is designedfor cardiology. In CT, MR and many angiographic procedures, the contrastinjector does not share the fluid path to the patient with any otherdevices. In cardiology, the situation is different. Presently,cardiologists use a manually activated manifold with several three-wayor four-way valves. These valves are used so a single fluid line canmeasure pressure, perform scout injections, and provide various fluidsduring manipulation of the catheter to get it into the proper vessel. Inthis embodiment of the invention, the disposable manifolds 215 areoperated by electronic solenoids or motors controlled by the ECS. Thusthe whole sequence of the procedure is automated to a great extent.

FIG. 13 provides additional detail. A sterile disposable manifold 215 isshown and is similar to those manufactured by North American InstrumentCorporation of Glen Falls, N.Y. The only difference is that manifold 215includes valve adaptor plugs 217, 218, 219 which mate with slots inquarter-turn solenoid heads 221, 222, 223. Although numerous matinggeometries are possible, there is a safety advantage if mating may beaccomplished in a single orientation. In the preferred embodimentdescribed in FIG. 13, a single orientation is assured by having slotslocated in the solenoid heads which are more narrow on one end than theother. Mounting pins 225 and 226 located on the solenoid mounting case227 mate with mounting holes 228, 229 on the disposable manifold 215 tosecure the manifold to the solenoid mounting case.

The ECS controls the position of the quarter-turn solenoids 231, 232,233 via control lines 235, 236, 237. The quarter-turn solenoids aresimple electromechanical devices which rotate ninety-degrees each timethey are energized. In the described system, the solenoids need onlyrotate in a single direction because three successive energizations isthe same as moving one quarter-turn in the opposite direction. It isalso important that the system is capable of determining the position ofthe manifolds to ensure that this information is available when power isfirst turned on and also to verify that the valves move as commanded.Simple position sensors are utilized for this purpose and send signalsto the ECS via sense lines 240, 241, and 242. In a preferred embodimentthe sensors are optical encoders for simplicity and reliability.

A doctor may activate the manifold via any type of remote control suchas hand switches, foot switches or verbally with the aid of voicerecognition equipment. This last possibility is illustrated by FIG. 14.There is a significant benefit in the ability of the doctor to activatea control for example by simply stating, “measure pressure,” and haveall the valves move to the proper position. Alternatively, the doctorcould say, “scout injection,” and the ECS operating in conjunction withthe voice recognition equipment 244 would set the valves to the properposition for that function. This would eliminate many of the separateactions which a doctor currently is required to perform in usingcurrently available systems. An additional advantage is that a doctorusing the system is able to operate the equipment while being physicallyfurther from the patient thus being able to avoid the damaging effectsof the x-ray radiation.

In those embodiments where the operator is in the feedback loop,additional feedback relating to system operation may be provided toenhance system performance. For example, the operator may receive audiofeedback related to operational characteristics such as speed, volumeinjected or pressure. Tone of an audible signal could be used such thata higher pitch would indicate a higher speed, greater volume, or greaterpressure. Alternatively, an audible click could be used to indicateinjection of each milliliter of fluid or the click repetition rate couldbe proportional to the pressure. Audible feedback allows the operator toreceive this information while the operator continues to monitor thepatient or the image on the display 163. In a preferred embodiment, theaudio feedback is transmitted to the operator via an ear phone which iseither hard wired or battery powered to eliminate an additionaldistraction in a busy room and to avoid the possibility of the patientbecoming alarmed as a result of the audio signal.

Alternatively, the additional feedback could be displayed on the videomonitor 163 along with the patient image. Providing the additionalfeedback visually avoids the possible distraction of others and isparticularly useful if it can be displayed without distracting theoperator from viewing the patient image. One method of simultaneousdisplay is the use of numbers on the monitor which indicate flow rate. Abar graph or a syringe outline which empties as the fluid is injectedare other options.

Although the present invention has been described in terms of preferredembodiments, the present description is given by way of example and isnot intended to be limiting to the scope of the invention described andclaimed herein.

1. A fluid delivery system, comprising: a reusable fluid path fordelivering fluid to multiple patients, the reusable fluid pathcomprising: a first portion in fluid communication with a first sourceof fluid medium; and a second portion in fluid communication with asecond source of fluid medium; a first pressurizing device associatedwith the first portion of the reusable fluid path; a second pressurizingdevice associated with the second portion of the reusable fluid path; aper-patient disposable fluid path adapted to be connected to thereusable fluid path and operable to deliver the first and second fluidmedia at least to a balloon catheter in a patient; and a control unit incommunication with the first and second pressurizing devices and adaptedto actuate the first and second pressurizing devices to deliver thefirst and second fluid media to a balloon on the balloon catheter. 2.The fluid delivery system of claim 1 wherein the first fluid mediumcomprises a contrast medium and the second fluid medium comprises adiluent medium.
 3. The fluid delivery system of claim 1 wherein theper-patient disposable fluid path comprises: a tube; a valve; and aper-patient connector.
 4. The fluid delivery system of claim 3 whereinthe valve of the per-patient disposable fluid path comprises a checkvalve.
 5. The fluid delivery system of claim 1 wherein the reusablefluid path further comprises a mixing apparatus.
 6. The fluid deliverysystem of claim 1 wherein the reusable fluid path further comprises apressurization pump.
 7. The fluid delivery system of claim 1 wherein thefirst pressurizing device comprises a pump.
 8. The fluid delivery systemof claim 7 wherein the pump is a peristaltic pump.
 9. The fluid deliverysystem of claim 1 wherein the reusable fluid path further comprises anair detector.
 10. The fluid delivery system of claim 1 wherein thesecond pressurizing device comprises a pump.
 11. The fluid deliverysystem of claim 10 wherein the pump is a peristaltic pump.
 12. The fluiddelivery system of claim 1, further comprising a handheld controlmechanism in communication with the control unit to control the firstand second pressurizing devices.
 13. The fluid delivery system of claim1 wherein the first and second fluid media at least partially inflatethe balloon.
 14. A method of delivering fluid media to a ballooncatheter in a patient using a fluid delivery system comprising areusable fluid path comprising a first portion in fluid communicationwith a first source of fluid medium and a second portion in fluidcommunication with a second source of fluid medium, a first pressurizingdevice associated with the first portion of the reusable fluid path, anda second pressurizing device associated with the second portion of thereusable fluid path, the method comprising: providing a per-patientdisposable fluid path adapted to be connected to the reusable fluid pathand operable to deliver one or both of the first and second fluid mediaat least to a balloon catheter in a patient connecting the per-patientdisposable fluid path to the reusable fluid path; and actuating one orboth of the first and second pressurizing devices to deliver one or bothof the first and second fluid media via the reusable and per-patientdisposable fluid paths at least to a balloon on the balloon catheter.15. The method of claim 14, further comprising: providing a control unitin communication with the first and second pressurizing devices tocontrol the operation thereof.
 16. The method of claim 14, furthercomprising: at least partially inflating the balloon with one or both ofthe first and second fluid media.
 17. The method of claim 14 wherein theactuating step comprises actuating both of the first and secondpressurizing devices to deliver both of the first and second fluid mediato the balloon.
 18. The method of claim 17, further comprising the stepof mixing the first and second fluid media.
 19. The method of claim 14wherein the first fluid medium comprises a contrast medium and thesecond fluid medium comprises a diluent medium.
 20. The method of claim14, further comprising: disconnecting the per-patient disposable fluidpath from the reusable fluid path.